1. Field of the Invention
The present invention relates to a manually operated trigger type dispenser attached to the mouth of a container, sucking liquid from the container into a cylinder and pressurizing and causing the liquid to flow out by reciprocation of a piston cooperating with traction of trigger, and also relates to a child proof mechanism.
2. Description of the Prior Art
The problem of destroying the ozone layer is now a great problem. Hence, dispensers which use no freon gas to pressurize liquid, and which are manually operated to pressurize and force out liquid, are drawing more and more attention. In the dispenser of this kind, a dispenser body is connected to the mouth of a container holding liquid to be dispensed by means of a connecting member such as a bottle cap, and a cylinder is integrally formed on the dispenser body, for example.
A trigger is pivotably attached to the dispenser body, and a piston is reciprocated in the cylinder in cooperation with traction of the trigger against an urging force of a return spring. When the piston is returned from the pushed-in position to the initial position, the interior of the cylinder is negatively pressurized. Then, a primary valve is opened and a secondary valve is closed. When the trigger is released, it is returned to the initial position by the urging force of the return spring, and the piston is also returned to the initial position in cooperation with the trigger. Under the negative pressure in the cylinder, the liquid is sucked from the container into the cylinder through the primary valve as the liquid excludes residual air in the cylinder. Upon pulling the trigger against the return spring, the piston is pushed into the cylinder to pressurize the liquid in the cylinder. The pressurized liquid opens the secondary valve and flows from the cylinder into a flowing-out passage formed in the dispenser body through the second valve. A cylindrical blind-ended nozzle formed separately from the dispenser body is provided at the front end of the passage. A spinner (a swirling member) is housed in the nozzle. The pressurized liquid presses the spinner against the rear bottom surface of the nozzle, is swirled by the spinner and flows out of an orifice (or a flow-out port) of the front surface of the nozzle as a spray flow. When the use of the dispenser is interrupted, the liquid is sucked up into the cylinder and is retained in it. When the trigger is pulled again, the pressurized liquid flows out immediately.
Normally, all the components of a dispenser such as a dispenser body, a trigger a piston and a nozzle are injection molded from a plastics material.
Since the dispenser is connected to the mouth of a container, the level of the center of the gravity of the container having the dispenser connected thereto is inevitably high and it becomes unstable as the level of the liquid in the container becomes reduced. If the container falls by mistake, the trigger is likely to hit against something to cause the liquid to flow out and some accident may happen. The traction force required for operating the trigger is not very large Even a child such as a baby can pull the trigger. If the child pulls the trigger by mistake, the liquid which has flowed out may enter an eye or the eyes of the child and/or adheres to the skin of the child and an accident is likely to occur.
A manually operated trigger type dispenser is provided with an accident preventing mechanism called a child proof mechanism in order to prevent an accident of this kind. In General, the child proof mechanisms are classified into two types, one which locks a trigger itself and forcibly prevents the trigger from swinging as disclosed in U.S. Pat. Nos. 4,558,821 (Tada) and 3,927,834 (Tada), and the other in which the orifice of a nozzle is covered with a nozzle cover in liquid tightness as disclosed in U.S. Pat. Nos. 4,406,480 (Gazulla) and 4,815,663 (Tada). In the child proof mechanism of a trigger lock type, a holder of the trigger must be provided on the dispenser body and an engaging hole for the holder must be formed in the trigger. This makes the structure of the accident preveting mechanism complicated and deteriorates its appearance.
As shown in FIGS. 6 and 7(A) and 7(B), a manually operated trigger type dispenser 110 provided with a nozzle cover type child proof mechanism has a nozzle cover 138, a nozzle cover 130 and a hinge 136 connecting the nozzle cover 138 to the nozzle 130. The nozzle 130, the nozzle cover 138 and the hinge 136 are integrally molded from a plastics material. An orifice 134 is formed in the substantially center of the front surface of the nozzle 130, and a cylindrical portion 140 which closely contacts the orifice 134 and ensures liquid tightness is formed on the rear surface (inner surface) of the nozzle cover 138. The nozzle cover 138 can be fixed to nozzle 130 irrespective of whether or not the orifice 134 is covered with the nozzle cover 138. As shown in FIG. 7(A), the nozzle cover 138 is rotated in the direction of an arrow and is pushed into a despression 111 formed in the front surface of nozzle 130. Then, an engaging piece 113 on the rear surface of the nozzle cover 138 is held between holding portions 115 and 117, and the cylindrical portion 140 closely contacts the front surface of the orifice 134 to cover the orifice 134 in liquid tightness (see FIGS. 6 and 7(B)). As shown in FIG. 7(B), the nozzle cover 138 is rotated in the direction of an arrow and pressed against the upper surface of the nozzle 130. Then, the cylindrical portion 138a on the front surface of the nozzle cover 138 engages an engaging groove 130c in the upper surface of the nozzle 130 so that the nozzle cover 138 is fixed to the nozzle 130. A trigger 112 has an upper end fitted in the lateral wall of a dispenser body and is connected to the dispenser body so as to rotate around a pivot 122. The trigger 112 is pressed against the rear surface of the nozzle 130 by the urging force of a return spring so that the initial position of the trigger is set.
Even if the container happens to fall by mistake and the trigger is swung, or a child happens to move the trigger mischievously, liquid is prevented from flowing out and thus an unexpected accident can be avoided when the orifice 134 is covered with the nozzle cover 138 in liquid tightness. Since the nozzle cover 138 is fixed to the upper surface of the nozzle 130, pressurized liquid from the orifice 134 does not hit against the nozzle cover 138 and is not scattered while the dispenser is being used.
Apparently, the shape of the child proof mechanism including a nozzle cover becomes complicated a little but its number of parts does not increase. The nozzle cover is held on the front surface of nozzle when the orifice of the nozzle is covered with the nozzle cover. Thus, the appearance is not deteriorated. When the orifice of the nozzle is not covered, the nozzle cover can engage the upper surface of the nozzle cover. Therefore, the dispenser gives no strange impression and no poor appearance. Recently, therefore, child proof mechanisms of a nozzle cover type have been generally used.
With the conventional dispenser provided with a child proof mechanism of a nozzle cover type, the operator holds the lower end portion of the nozzle cover 138 with the finger and pulls it toward him or her. When the pulling force (the traction force) is larger than the force which holds the nozzle cover (the holding force or locking force), the nozzle cover is released immediately and the orifice 134 of the nozzle 130 is opened.
It is well known that, with the conventional dispenser, the child proof mechanism is released by pulling the nozzle cover. A child can release the child proof mechanism very easily, and thus the dispenser is apt to lose its child proof function.